"""Git utilities for HYDRA autoresearch branch management."""
import os
import subprocess

REPO_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))


def run_git(*args: str, check: bool = True) -> subprocess.CompletedProcess:
    """Run a git command in the repo directory.

    Args:
        *args: Git command arguments.
        check: Whether to raise on non-zero exit code.

    Returns:
        Completed process with stdout/stderr captured.
    """
    return subprocess.run(
        ["git"] + list(args),
        cwd=REPO_DIR,
        capture_output=True,
        text=True,
        check=check,
    )


def current_branch() -> str:
    """Return the current git branch name.

    Returns:
        Branch name string.
    """
    result = run_git("rev-parse", "--abbrev-ref", "HEAD")
    return result.stdout.strip()


def current_commit_short() -> str:
    """Return the current HEAD commit short hash (7 chars).

    Returns:
        7-character commit hash.
    """
    result = run_git("rev-parse", "--short=7", "HEAD")
    return result.stdout.strip()


def create_branch(name: str) -> None:
    """Create and switch to a new branch.

    Args:
        name: Branch name to create.
    """
    run_git("checkout", "-b", name)


def commit_all(message: str) -> str:
    """Stage all changes, commit, and return short hash.

    Args:
        message: Commit message.

    Returns:
        Short commit hash after committing.
    """
    run_git("add", "-A")
    run_git("commit", "-m", message, check=False)
    return current_commit_short()


def reset_to(commit: str) -> None:
    """Hard reset to a specific commit, discarding all changes.

    Args:
        commit: Commit hash (short or full) to reset to.
    """
    run_git("reset", "--hard", commit)


def get_last_n_diffs(n: int = 3) -> list[str]:
    """Get the last N commit diffs (--stat format) for meta-agent context.

    Args:
        n: Number of recent commits to retrieve.

    Returns:
        List of diff stat strings, one per commit (truncated to 500 chars).
    """
    result = run_git("log", f"-{n}", "--format=%H", check=False)
    hashes = [h for h in result.stdout.strip().split("\n") if h]
    diffs: list[str] = []
    for h in hashes:
        diff_result = run_git("show", "--stat", h, check=False)
        diffs.append(diff_result.stdout[:500])
    return diffs